1. Field of the Invention
The present invention relates to an analytical method and an analytical apparatus using test strips, and more particularly to an analytical method and an analytical apparatus in which a biological sample such as urine or blood is caused to develop a color reaction in reagent sections on test strips.
2. Description of the Prior Art
A method of analyzing using test strips, each of which is made by impregnating small strips of felt or the like with reagents to form a plurality of reagent sections or test sections, and then by bonding the small strips to a plastic stick, has been adopted, for example, in a screening test for group examination and diagnosis of diseases. An apparatus capable of automatically carrying out operations necessary for such a method is disclosed in Japanese patent unexamined publication 61-91571. Note that this Japanese patent unexamined publication corresponds to U.S. Pat. No. 4,876,204.
In the analytical apparatus disclosed in the above-cited Japanese patent unexamined publication 61-91571, a test strip supplied from an automatic supply device is held by a handling device, and the test strip is dipped into a sample liquid in a sample container. After that, the test strip is lifted out of the sample container and transferred to a reaction table. The test strip is then transported to a light detecting portion where colored reagent sections are measured.
This reference also discloses an arrangement for measuring a sample liquid level in the sample container and giving an advance notice of insufficiency of the sample liquid, prior to dipping the test strip into the sample liquid. Further, an arrangement for detecting the liquid level in bottles is disclosed in U.S. Pat. No. 4,451,433, by which the liquid level of reagent solutions supplied to a chemical analyzer is detected by a pair of electrodes.
In the apparatus of the above-cited Japanese patent unexamined publication 61-91571, those samples of whose volumes are insufficient for thorough immersion of the reagent sections of the test strip are all disabled from measuring and, therefore, automatic measurement cannot be achieved. More specifically, the test strip comprises a plastic stick having a plurality of reagent sections arranged in the direction of stick length. To make all the reagent sections thoroughly dipped in a sample, it is required that a sufficient volume of sample has been sampled in the sample container. In the practical working field, however, samples are occasionally used having sample volumes that are too small to provide a sufficient liquid depth in the sample containers.